If there's one thing that people couldn't stop talking about at this week's Google I/O, the search giant's annual developer conference, it was Apple.

It makes sense. Apple and Google are widely held to be bitter rivals in the mobile space. Steve Jobs was once so angry about Android allegedly ripping off the iPhone, he vowed to go "thermonuclear" on Google.

Everything Google announced this week — and everything that Google has announced in mobile since the launch of the first Android phone in 2009 — has been to fire shots across the bow at Apple.

Right?

Except that they aren't really competing at all.

Apple and Google are two completely different kinds of companies. And while they have similar products — iOS and Android, Apple Maps and Google Maps, the App Store and Google Play — they're in the business for totally different reasons.

You can see it in the two companies' mission statements.

Apple's:

Apple designs Macs, the best personal computers in the world, along with OS X, iLife, iWork and professional software. Apple leads the digital music revolution with its iPods and iTunes online store. Apple has reinvented the mobile phone with its revolutionary iPhone and App Store, and is defining the future of mobile media and computing devices with iPad.

Translation: Apple is a hardware company. It doesn't give a damn about your personal data. It just wants to sell lots of phones and computers at prices that maximize its profits over the long-term (that's key — Apple, like most successful tech companies, plans way beyond the current quarter and year). It makes good-looking, basic apps that it builds into its hardware because that's part of making sure they just work. But it's all about the hardware.

Google's:

Google’s mission is to organize the world’s information and make it universally accessible and useful.

Google wants data. It can't get enough of the stuff. The more data, the better. In fact, three of the top-10 free apps on Apple's iTunes App Store are from Google. Zero of them are from Apple.

Google talks a big talk about getting the next billion people online and all kinds of other philanthropic projects. But Google is a technology company that makes more than 90% of its money selling ads. The more data it has about the audience it's selling ads against, the more valuable those ads are, and the more money advertisers will pay for them.

Google bought Android in the first place as a way to hedge against a competitor launching a mobile operating system that used a competing search engine, which would eat away at Google's ad business. With 79% market share, there are a lot of people using Android — and, crucially, who aren't using iOS or anything else.

But the more you use Android, the more data you give to Google. That data helps it sell ads. If Google is getting the next billion people online, you can bet it's imagining a billion new people looking at Google's ads.

There are pleasant side effects here: The more data Google has, the more accurate its products become, which in turn helps it attract more users, and so on in a virtuous cycle of product improvement.

Google Now takes your data and tells you when you need to leave for the airport. Google Photos can tell which of your photos have your mom in them. Google search knows that you're probably looking for this article right here. Hi!

Apple isn't stupid. If Apple wanted to, it could make a cheaper iPhone and break into the developing markets by the end of this year, eating at Android's market dominance. They have the talent, and they definitely have the cash.

But Apple is doing just fine without being everywhere. As long as enough people are paying enough money for its devices, Apple and its shareholders will be happy.

Google needs to be everywhere because Google's business is based on data.